// sd card CRC algorithms
// Dan Newman, February 2013

#include "Compat.hh"
#include <stdint.h>
#include <avr/pgmspace.h>
#include "sd_crc.h"

// 7bit CRC with polynomial x^7 + x^3 + 1
// A table driven form can be found in the Linux kernel under lib/crc7.c.
// Bitwise forms may be generated using pycrc with the parameters
//
//   pycrc --width=7 --poly=9 --reflect-in=0 --reflect-out=0
//         --xor-out=0 --xor-in=0 --generate c --algorithm=bit-by-bit-fast

#define SAVE_SPACE

#ifdef SAVE_SPACE

uint8_t sd_crc7(const uint8_t *data, uint8_t len)
{
    uint8_t crc = 0x00;
    for (uint8_t i = 0; i < len; i++)
    {
	uint8_t d = data[i];
	for (uint8_t j = 0; j < 8; j++)
	{
	    crc <<= 1;
	    if ( (d & 0x80) ^ (crc & 0x80) )
		crc ^= 0x09;
	    d <<= 1;
	}
    }
    return (crc << 1) | 1;
}

#else

static const uint8_t crc7_table[256] PROGMEM = {
     0x00, 0x09, 0x12, 0x1b, 0x24, 0x2d, 0x36, 0x3f,
     0x48, 0x41, 0x5a, 0x53, 0x6c, 0x65, 0x7e, 0x77,
     0x19, 0x10, 0x0b, 0x02, 0x3d, 0x34, 0x2f, 0x26,
     0x51, 0x58, 0x43, 0x4a, 0x75, 0x7c, 0x67, 0x6e,
     0x32, 0x3b, 0x20, 0x29, 0x16, 0x1f, 0x04, 0x0d,
     0x7a, 0x73, 0x68, 0x61, 0x5e, 0x57, 0x4c, 0x45,
     0x2b, 0x22, 0x39, 0x30, 0x0f, 0x06, 0x1d, 0x14,
     0x63, 0x6a, 0x71, 0x78, 0x47, 0x4e, 0x55, 0x5c,
     0x64, 0x6d, 0x76, 0x7f, 0x40, 0x49, 0x52, 0x5b,
     0x2c, 0x25, 0x3e, 0x37, 0x08, 0x01, 0x1a, 0x13,
     0x7d, 0x74, 0x6f, 0x66, 0x59, 0x50, 0x4b, 0x42,
     0x35, 0x3c, 0x27, 0x2e, 0x11, 0x18, 0x03, 0x0a,
     0x56, 0x5f, 0x44, 0x4d, 0x72, 0x7b, 0x60, 0x69,
     0x1e, 0x17, 0x0c, 0x05, 0x3a, 0x33, 0x28, 0x21,
     0x4f, 0x46, 0x5d, 0x54, 0x6b, 0x62, 0x79, 0x70,
     0x07, 0x0e, 0x15, 0x1c, 0x23, 0x2a, 0x31, 0x38,
     0x41, 0x48, 0x53, 0x5a, 0x65, 0x6c, 0x77, 0x7e,
     0x09, 0x00, 0x1b, 0x12, 0x2d, 0x24, 0x3f, 0x36,
     0x58, 0x51, 0x4a, 0x43, 0x7c, 0x75, 0x6e, 0x67,
     0x10, 0x19, 0x02, 0x0b, 0x34, 0x3d, 0x26, 0x2f,
     0x73, 0x7a, 0x61, 0x68, 0x57, 0x5e, 0x45, 0x4c,
     0x3b, 0x32, 0x29, 0x20, 0x1f, 0x16, 0x0d, 0x04,
     0x6a, 0x63, 0x78, 0x71, 0x4e, 0x47, 0x5c, 0x55,
     0x22, 0x2b, 0x30, 0x39, 0x06, 0x0f, 0x14, 0x1d,
     0x25, 0x2c, 0x37, 0x3e, 0x01, 0x08, 0x13, 0x1a,
     0x6d, 0x64, 0x7f, 0x76, 0x49, 0x40, 0x5b, 0x52,
     0x3c, 0x35, 0x2e, 0x27, 0x18, 0x11, 0x0a, 0x03,
     0x74, 0x7d, 0x66, 0x6f, 0x50, 0x59, 0x42, 0x4b,
     0x17, 0x1e, 0x05, 0x0c, 0x33, 0x3a, 0x21, 0x28,
     0x5f, 0x56, 0x4d, 0x44, 0x7b, 0x72, 0x69, 0x60,
     0x0e, 0x07, 0x1c, 0x15, 0x2a, 0x23, 0x38, 0x31,
     0x46, 0x4f, 0x54, 0x5d, 0x62, 0x6b, 0x70, 0x79 };

uint8_t sd_crc7(const uint8_t *data, uint8_t len)
{
    uint8_t crc = 0x00;
    while (len--)
	crc = pgm_read_byte((const uint8_t *)&crc7_table[(crc << 1) ^ (*data++)]);
    return (crc << 1) | 1;
}

#endif

// ITU-T V.41 16 bit CRC with polynomial 0x1021
// A table driven version resides in the Linux kernel under
// lib/crc-itu-t.c

#if (0) // #ifdef SAVE_SPACE

// saves 1024 Bytes table space, but is a little bit slower
uint16_t sd_crc16(const uint8_t *data, uint16_t len)
{
  uint16_t crc = 0;
  uint16_t osum;
  uint8_t byte;
  uint8_t i;

  while(len--)
  {
    byte = *data++;
    for(i = 8; i; i--)
    {
      osum = crc;
      crc <<= 1;
      if(byte & 0x80)
        crc ^= 0x1021;
      if(osum & 0x8000)
        crc ^= 0x1021;
      byte <<= 1;
    }
  }
  return crc;
}

#else

static const uint16_t crc16_table[256] PROGMEM = {
    0x0000, 0x1021, 0x2042, 0x3063, 0x4084, 0x50A5, 0x60C6, 0x70E7,
    0x8108, 0x9129, 0xA14A, 0xB16B, 0xC18C, 0xD1AD, 0xE1CE, 0xF1EF,
    0x1231, 0x0210, 0x3273, 0x2252, 0x52B5, 0x4294, 0x72F7, 0x62D6,
    0x9339, 0x8318, 0xB37B, 0xA35A, 0xD3BD, 0xC39C, 0xF3FF, 0xE3DE,
    0x2462, 0x3443, 0x0420, 0x1401, 0x64E6, 0x74C7, 0x44A4, 0x5485,
    0xA56A, 0xB54B, 0x8528, 0x9509, 0xE5EE, 0xF5CF, 0xC5AC, 0xD58D,
    0x3653, 0x2672, 0x1611, 0x0630, 0x76D7, 0x66F6, 0x5695, 0x46B4,
    0xB75B, 0xA77A, 0x9719, 0x8738, 0xF7DF, 0xE7FE, 0xD79D, 0xC7BC,
    0x48C4, 0x58E5, 0x6886, 0x78A7, 0x0840, 0x1861, 0x2802, 0x3823,
    0xC9CC, 0xD9ED, 0xE98E, 0xF9AF, 0x8948, 0x9969, 0xA90A, 0xB92B,
    0x5AF5, 0x4AD4, 0x7AB7, 0x6A96, 0x1A71, 0x0A50, 0x3A33, 0x2A12,
    0xDBFD, 0xCBDC, 0xFBBF, 0xEB9E, 0x9B79, 0x8B58, 0xBB3B, 0xAB1A,
    0x6CA6, 0x7C87, 0x4CE4, 0x5CC5, 0x2C22, 0x3C03, 0x0C60, 0x1C41,
    0xEDAE, 0xFD8F, 0xCDEC, 0xDDCD, 0xAD2A, 0xBD0B, 0x8D68, 0x9D49,
    0x7E97, 0x6EB6, 0x5ED5, 0x4EF4, 0x3E13, 0x2E32, 0x1E51, 0x0E70,
    0xFF9F, 0xEFBE, 0xDFDD, 0xCFFC, 0xBF1B, 0xAF3A, 0x9F59, 0x8F78,
    0x9188, 0x81A9, 0xB1CA, 0xA1EB, 0xD10C, 0xC12D, 0xF14E, 0xE16F,
    0x1080, 0x00A1, 0x30C2, 0x20E3, 0x5004, 0x4025, 0x7046, 0x6067,
    0x83B9, 0x9398, 0xA3FB, 0xB3DA, 0xC33D, 0xD31C, 0xE37F, 0xF35E,
    0x02B1, 0x1290, 0x22F3, 0x32D2, 0x4235, 0x5214, 0x6277, 0x7256,
    0xB5EA, 0xA5CB, 0x95A8, 0x8589, 0xF56E, 0xE54F, 0xD52C, 0xC50D,
    0x34E2, 0x24C3, 0x14A0, 0x0481, 0x7466, 0x6447, 0x5424, 0x4405,
    0xA7DB, 0xB7FA, 0x8799, 0x97B8, 0xE75F, 0xF77E, 0xC71D, 0xD73C,
    0x26D3, 0x36F2, 0x0691, 0x16B0, 0x6657, 0x7676, 0x4615, 0x5634,
    0xD94C, 0xC96D, 0xF90E, 0xE92F, 0x99C8, 0x89E9, 0xB98A, 0xA9AB,
    0x5844, 0x4865, 0x7806, 0x6827, 0x18C0, 0x08E1, 0x3882, 0x28A3,
    0xCB7D, 0xDB5C, 0xEB3F, 0xFB1E, 0x8BF9, 0x9BD8, 0xABBB, 0xBB9A,
    0x4A75, 0x5A54, 0x6A37, 0x7A16, 0x0AF1, 0x1AD0, 0x2AB3, 0x3A92,
    0xFD2E, 0xED0F, 0xDD6C, 0xCD4D, 0xBDAA, 0xAD8B, 0x9DE8, 0x8DC9,
    0x7C26, 0x6C07, 0x5C64, 0x4C45, 0x3CA2, 0x2C83, 0x1CE0, 0x0CC1,
    0xEF1F, 0xFF3E, 0xCF5D, 0xDF7C, 0xAF9B, 0xBFBA, 0x8FD9, 0x9FF8,
    0x6E17, 0x7E36, 0x4E55, 0x5E74, 0x2E93, 0x3EB2, 0x0ED1, 0x1EF0
};

uint16_t sd_crc16(const uint8_t *data, uint16_t len) {
    uint16_t crc = 0;
    while (len--)
	crc = (crc << 8) ^
	    pgm_read_word(&crc16_table[((crc >> 8) ^ (*data++)) & 0xFF]);
    return crc;
}


#endif // SAVE_SPACE
